Composer doesn\'t run correctly in Cygwin if you try to install it \"globally\".
Putting composer.phar into /usr/local/bin/composer, then trying to run it will result in
I suggest you use babun, it is based cygwin, but you can install package by pact, you can do this:
pact install php php-json php-phar
php -r "readfile('https://getcomposer.org/installer');" | php
then enjoy yourself.